[U-Boot] [PATCH 0/6] ARMv7: Add HYP mode switching support

[Andre Przywara]

On 05/31/2013 08:11 AM, Christoffer Dall wrote:
> On Mon, May 06, 2013 at 03:17:44PM +0200, Andre Przywara wrote:
>> (for GIT URL and Changelog see below)
>>
>> ARM CPUs with the virtualization extension have a new mode called
>> HYP mode, which allows hypervisors to safely control and monitor
>> guests. The current hypervisor (KVM and Xen) implementations
>> require the kernel to be entered in that HYP mode.
>>
>> This patch series introduces a configuration variable
>> CONFIG_ARMV7_VIRT which enables code to switch all cores into HYP
>> mode. This is done automatically during execution of the bootm
>> command (but could also be done earlier - U-Boot runs fine in HYP
>> mode without MMU usage).
>
> I forget the u-boot specifics here, but if you boot over networking, for
> example, does that eventually end up calling bootm or would Hyp mode not
> be entered in this case?

Despite the naming "bootm" is eventually always called when booting 
Linux, even bootz is a wrapper around this. Same with network boot. So 
unless you show me a case where this isn't, I think this is fine.

Regards,
Andre.

> I'm only raising this issue because it's important to minimize the hoops
> and efforts for booting in Hyp mode, since it's harmless to do so
> regardless of the linux kernel we're booting.
>
> [...]
>
> -Christoffer
>